The present invention provides a magnetic fastener usable for various types of bags such as shoulder and rucksacks, and for various types of boxes and belts, as well as for holding a door against a wall.
A fastener device that merely use the strength of the magnetic attraction to fasten mating parts does not operate properly when a force or an impact stronger than the attraction force of the permanent magnet is exerted on the male and female members, as the mating parts will disengage.
To overcome the defect, there has been proposed a fastener comprising a ferromagnetic female member which has a hole for receiving a projection of a male member. The projection has an enlarged head and a permanent magnet at the base of the projection. With this type of fastener means, the female member is attracted by the permanent magnet of the male member when the projection of the male member is inserted in the hole of the female member to effect tentative engagement between the two members. By twisting the projection, the enlarged head of the projection is disposed on a plate portion near the periphery of the hole in the female member to firmly lock the two members.
Although firm engagement of the male and female members is achieved in this type of fastener means, it is rather troublesome to twist the projection of the male member every time it is inserted in the female member, and more particularly, to pull the two members apart in addition to twisting the projection of the male member for detaching the two members.
In view of the foregoing, various improvements have been proposed to provide a fastener means which is easy in manipulation. The fastener means proposed by JP Publication No. Hei 3-14983 is a typical example.
In JP 3-14983, the projection of the male member has a laterally extending head portion which is either made of or provided with a permanent magnet. The female member has a hole for receiving the projection of the male member, and when the projection of the male member is inserted therein, a ferromagnetic plate slideably incorporated in the female member is attracted to the projection, so that the ferromagnetic plate becomes locked with said laterally extending portion of the projection when a force is exerted to pull the male member out of the female member.
The fastener of this type is still defective in that component parts of the fastener are not necessarily easy to assemble, and the appearance of the fastener means is not quite appealing.